Spum yarn

ABSTRACT

A spun yarn comprising poly(trimethylene terephthalate) staple fibers at a content of at least 15% by weight, the spun yarn having an elastic recovery percentage of elongation at 5% elongation (%) ≧0.1X+70 (wherein X represents the content of poly(trimethylene terephthalate) staple fibers in the spun yarn (wt %)). The spun yarn is excellent in knitting and weaving characteristics, stretchability and stretch-back property and in shape stability and durability when worn for a prolonged period of time.

TECHNICAL FIELD

[0001] The present invention relates to a spun yarn comprisingpoly(trimethylene terephthalate) staple fibers.

BACKGROUND ART

[0002] Spun yarns produced from natural fibers such as cotton, wool andlinen (ramie) as raw materials have excellent feelings peculiar to therespective fibers, so that they find wide applications. However, spunyarns produced totally from such natural fibers have drawbacks inhandling characteristics and in durability when worn, such as relativelylow strength, large shrinkage after washing and large configurationalchange.

[0003] Therefore, in order to cope with such drawbacks, wide use is madeof blended spun yarns produced by blend spinning (mix spinning) naturalfibers and staples (discontinuous fibers or short fibers) of syntheticfibers. A representative example of the synthetic fibers used in theblend spinning is a poly(ethylene terephthalate) fiber. The blendspinning thereof exerts apparent effects on improvements in strength andin shape stability. However, the poly(ethylene terephthalate) fiber haslarge Young's modulus, so that its feel is hard. Thus, the poly(ethyleneterephthalate) fiber has a fatal drawback in that when blend-spun withnatural fibers, the excellent feel of natural fibers would inevitably bedeteriorated even if the blending ratio thereof is low.

[0004] Recently, appropriate stretchability and stretch-back propertyare increasingly demanded on woven fabrics and knit fabrics forclothing. CSY (core spun yarn) having a core constituted of an elasticyarn, such as spandex, is well known as a spun yarn with stretchabilityand stretch-back property. However, spandex poses such a problem thatembrittlement by chemicals, such as chlorine, is serious andcolorfastness thereof is low. Further, CSY has drawbacks in thatbreakage of spandex constituting a core yarn (namely, core breakage) islikely to occur during the manufacturing or aftertreatment, and thataccurate insertion of spandex in the core is technically difficult. Yarnhaving spandex protruding outside inflicts a loss in manufacturing,thereby lowering the yield and increasing the manufacturing cost.Because of these problems, there is a demand on a spun yarn withexcellent stretchability produced without the use of spandex.

[0005] On the other hand, poly(trimethylene terephthalate) fibers arepublicly known as fibers of low initial stretching resistance (Young'smodulus) and high elastic recovery. Japanese Patent Publication No.49(1974)-21256 discloses a crimped fiber with a flexure recovery of atleast 70% wherein a poly(butylene terephthalate) fiber and apoly(trimethylene terephthalate) fiber are contained in a proportion of50 wt % or more, and further discloses a staple fiber obtained bycutting the crimped fiber into given lengths. Japanese Patent Laid-OpenNo. 11(1999)-189938 discloses a staple fiber of poly(trimethyleneterephthalate) having its elastic recovery percentage of elongation andflexure recovery enhanced by thermal treatment.

[0006] In both of these published inventions, there is no particulardisclosure at all with respect to the most suitable spun yarnspecifications and characteristics regarding the spun yarn produced fromthe above staple fibers, although the elastic recovery percentage ofelongation and flexure recovery of poly(trimethylene terephthalate)filament and staple fibers are disclosed.

DISCLOSURE OF THE INVENTION

[0007] It is an object of the present invention to provide apoly(trimethylene terephthalate) spun yarn which is excellent inknitting and weaving characteristics and excellent in at least one ofstretchability, stretch-back property, shape stability and durabilitywhen worn for a prolonged period of time, etc., and by which a wovenfabric and knit fabric making the most of the feeling of other materialblended with poly(trimethylene terephthalate) staple fibers can beobtained.

[0008] The inventors have made extensive and intensive investigationswith a view toward attaining the above object. As a result, it has beenfound that the above object can be attained by the use of a spun yarnwith specified properties comprising poly(trimethylene terephthalate)staple fibers. The present invention has been completed on the basis ofthis finding.

[0009] That is, the present invention is as follows.

[0010] 1. A spun yarn comprising poly(trimethylene terephthalate) staplefibers (discontinuous fibers or short fibers) at a content of at least15% by weight, the spun yarn having an elastic recovery percentage ofelongation at 5% elongation satisfying the formula:

elastic recovery percentage of elongation at 5% elongation (%) ≧0.1X+70  (a)

[0011] wherein X represents the content of poly(trimethyleneterephthalate) staple fibers in the spun yarn (% by weight).

[0012] 2. The spun yarn according to item 1 above, which is a compositespun yarn comprising poly(trimethylene terephthalate) staple fibers andother fibers, wherein the content of poly(trimethylene terephthalate)staple fibers is in the range of 15 to 70% by weight.

[0013] 3. The spun yarn according to item 1 or 2 above, which exhibitsan elongation at break (rupture) of 10% or greater.

[0014] 4. The spun yarn according to item 1, 2 or 3 above, whichexhibits a tenacity (tensile strength) and elongation product of 15cN·%/dtex or greater.

[0015] 5. The spun yarn according to any of items 1 to 4 above, whichexhibits an I-coefficient or L-coefficient of 1.0 to 2.5.

[0016] 6. The spun yarn according to any of items 1 to 5 above, to whicha finishing oil has been applied, the finishing oil containing an alkylphosphate salt whose alkyl group has 8 to 18 carbon atoms on theaverage.

[0017] In the present invention, the elastic recovery percentage ofelongation at 5% elongation (%), elongation at break (%), tenacity andelongation product (cN·%/dtex), initial stretching resistance (cN/dtex),I-coefficient and L-coefficient were measured in the following manner.

[0018] (1) Elastic Recovery Percentage of Elongation at 5% Elongation

[0019] Initial load specified in JIS-L-1095 (method of testing a commonspun yarn) was applied to each spun yarn, and the length thereof wasextended to given elongation L (5%=1 cm) with the use of constant-rateextension type tensile tester in accordance with the method of measuringan elastic recovery percentage of elongation (method A) under suchconditions that the chuck spacing was 20 cm and that the stretch speedwas 50% of the chuck spacing per minute. The spun yarn was allowed tostand still for 1 min, and the original length thereof was restored atthe same speed. The spun yarn was allowed to stand still for 3 min, andagain the length thereof was extended to point L₁ at which the initialload was applied at the same speed. The elastic recovery percentage ofelongation Ec (%) was calculated by the formula:

Ec(%)={(L−L ₁)/L}×100

[0020] The test was performed 5 times, and the measurements wereaveraged.

[0021] (2) Elongation at Break, Tenacity and Elongation Product andInitial Stretching Resistance

[0022] Initial load specified in JIS-L-1095 (method of testing a commonspun yarn) was applied to each spun yarn, and a tensile test thereof wasperformed with the use of constant-rate extension type tensile testerunder such conditions that the chuck spacing was 30 cm and that thestretch speed was 100% of the chuck spacing per minute. Thus, thetenacity at break (cN/dtex) and elongation at break (%) (ratio of extentof elongation at break to chuck spacing) were determined.

[0023] The tenacity and elongation product was calculated by theformula:

Tenacity and elongation product (cN·%/dtex)=tenacity at break(cN/dtex)×elongation at break (%)

[0024] The initial stretching resistance (cN/dtex) was determined by, ona drawn load—elongation curve, identifying a point of maximum loadchange vs. elongation change at a proximity to the original point and bymeasuring the gradient of a tangential line at the identified point.

[0025] The test was performed 20 times, and the measurements wereaveraged.

[0026] (3) I-Coefficient and L-Coefficient

[0027] The I-coefficient and L-coefficient are coefficients expressingthe uniformity of yarn, and are also referred to as unevenness indexes.

[0028] The I-coefficient and L-coefficient are values obtained bymeasuring U% (average deviation percentage of weight of yarn per unitlength thereof) by means of a USTER-TESTER-3 manufactured by ZellwegerUster K. K. and dividing the measurement by theoretical limit uniformityU_(lim), and calculated by the following formulae depending on themagnitude of the number of constituent staple fibers.

[0029] (1) When the number of constituent staple fibers is 64 or less,

I-coefficient=U%×(number of constituent staple fibers)^(1/2)/80   (b)

[0030] (2) When the number of constituent staple fibers exceeds 64,

L-coefficient=U%×(number of constituent staple fibers)^(1/3)/40   (c)

[0031] Herein, the number of constituent staple fibers refers to theaverage number of staple fibers lying in a section of spun yarn, andcalculated by the formula:

Number of constituent staple fibers=fineness of spun yarn (dtex)/averagefineness of staple fiber (dtex).

[0032] When staple fibers of different fineness values are blend-spun,for example, when blend spinning is performed with the use of staplefibers of fineness D₁ (dtex) at a blending ratio of W₁ (%) and staplefibers of fineness D₂ (dtex) at a blending ratio of W₂ (%), the numberof constituent staple fibers is calculated by the formula:

Number of constituent staple fibers=fineness of spun yarn (dtex)×(W₁/100)/D₁+fineness of spun yarn (dtex)×(W ₂/100)/D₂

[0033] The present invention will be described in detail below.

[0034] The spun yarn of the present invention contains poly(trimethyleneterephthalate) staple fibers in an amount of at least 15 wt %. That is,the spun yarn of the present invention may be a spun yarn consisting 100wt % of poly(trimethylene terephthalate) staple fibers, and also may bea composite spun yarn produced by blend spinning of poly(trimethyleneterephthalate) staple fibers and at least one other staple fibers,wherein poly(trimethylene terephthalate) staple fibers are contained inan amount of 15 wt % or more. The incorporation of poly(trimethyleneterephthalate) staple fibers in an amount of 15 wt % or more enablesobtaining a spun yarn which exhibits a high elastic recovery percentageof elongation and which is excellent in stretchability, stretch-backproperty and shape stability upon long-term wearing.

[0035] The spun yarn of the present invention, when consisting totallyof poly(trimethylene terephthalate) staple fibers, exhibits the higheststretchability and stretch-back property. However, on the other hand,the poly(trimethylene terephthalate) staple fibers, when formed into acomposite spun yarn with other fibers, can exhibit further excellentcharacteristics. That is, composite spinning of poly(trimethyleneterephthalate) staple fibers with other fibers enables obtaining a spunyarn which while satisfactorily making the most of the feeling ofblended other fibers, exerts excellent functions with respect tostretchability, stretch-back property, shape stability, etc.

[0036] In the composite spun yarn, the content of poly(trimethyleneterephthalate) staple fibers is preferably in the range of 15 to 70 wt%. For more effectively utilizing the feeling of other fibers, thecontent is still preferably in the range of 20 to 40 wt %. When thecontent of poly(trimethylene terephthalate) staple fibers is 15 wt % orgreater, there can be obtained a spun yarn which has an elastic recoverypercentage of elongation at 5% elongation satisfying the above formula(a) and exhibits a satisfactory stretch-back property. Further, when thecontent of poly(trimethylene terephthalate) staple fibers is 70 wt % orless, there can be obtained a spun yarn which can satisfactorily makethe most of the feeling of blended other fibers.

[0037] The other fibers to be blend-spun with the poly(trimethyleneterephthalate) staple fibers are not particularly limited, and can beselected in conformity with the properties demanded for desiredcommodity. The blend-spun other fibers may be, for example, any ofnatural fibers such as cotton, linen (ramie), wool and silk; chemicalfibers such as cupra, viscose, polynosic, purified cellulose and acetatefibers; polyester fibers such as poly(ethylene terephthalate) andpoly(butylene terephthalate) fibers; synthetic fibers such as acrylicand polyamide fibers; copolymer type fibers derived from these; andconjugate fibers from identical polymer or different types of polymers(side-by-side type, eccentric sheath core type, etc.).

[0038] The method of blending fibers for obtaining a composite spun yarnis not particularly limited. For example, use can be made of the methodwherein raw staple fibers are blended with poly(trimethyleneterephthalate) staple fibers in a blowing and scutching step or acarding step, the method wherein slivers are piled one upon another intoa composite form in a drawing step or a mixing gill step, or the methodwherein, in a spinning step, a plurality of slivers or roving yarns aresupplied and a spinning (CSIROSPUN system) is carried out thereon.

[0039] More specifically, for example, a composite spun yarn composed ofcotton and poly(trimethylene terephthalate) staple fibers is preferablyproduced by, in a spinning process according to cotton spinning system,passing staple fibers consisting 100 wt % of poly(trimethyleneterephthalate) staple fibers (preferably a fiber length of 38 mm)through a carding machine to form a sliver and, in a subsequent drawingstep, doubling the formed sliver with a cotton sliver into a compositeform. On the other hand, a composite spun yarn composed of wool or linen(ramie) and poly(trimethylene terephthalate) staple fibers is preferablyproduced by, in a spinning process according to worsted spinning system,passing staple fibers consisting 100 wt % of poly(trimethyleneterephthalate) staple fibers (bias cut into fiber lengths of 64 mm orgreater) through a roller carding machine to form a sliver andthereafter doubling the formed sliver with a wool or linen (ramie)sliver into a composite form by means of a mixer (mixing gill orbobbiner equipped with porcupine roller). Further, when it is intendedto produce a composite spun yarn composed of cashmere or lamb's wool andpoly(trimethylene terephthalate) staple fibers by a spinning processaccording to woolen spinning system, the application to roller cardingmachine is preferably performed after the mixing at raw staple fiberpreparation.

[0040] The spun yarn of the present invention has an elastic recoverypercentage of elongation at 5% elongation satisfying the above formula(a). The elastic recovery percentage of elongation at 5% elongation ofthe spun yarn of the present invention is preferably in the range of 75to 100%, still more preferably, 80 to 100%.

[0041] When the elastic recovery percentage of elongation at 5%elongation satisfies the above formula (a), satisfactory stretch-backproperty can be realized. The knit fabric or woven fabric from the spunyarn is excellent in fitness as a clothing. Further, deforming anddimensional change thereof are slight irrespective of long-term wearingor repeated washings. That is, the knit fabric or woven fabric from thespun yarn is excellent in shape stability.

[0042] In this connection, the spun yarn from poly(ethyleneterephthalate) staple fibers or poly(butylene terephthalate) staplefibers in place of the poly(trimethylene terephthalate) staple fiberscannot satisfy the above formula (a).

[0043] The elongation at break of the spun yarn of the present inventionis preferably 10% or greater, still preferably in the range of 20 to60%. When the elongation at break falls within this range, theoccurrence of yarn breakage at knitting or weaving is less, therebyrealizing satisfactory knitting and weaving characteristics and enablingobtaining a woven fabric of excellent stretchability.

[0044] The tenacity and elongation product of the spun yarn of thepresent invention is preferably 15 cN·%/dtex or greater, stillpreferably in the range of 20 to 100 cN·%/dtex. When the tenacity andelongation product is 15 cM·%/dtex or greater, the yarn exhibits hightoughness. Thus, such effects as an increase of resistance to ruptureunder instantaneous high stress and a decrease of tenacity andelongation deterioration under repeated stress can be exerted.Consequently, a woven fabric of high impact resistance and durability,which is most suitable for sports clothing and the like, can beobtained.

[0045] The spun yarn of the present invention exhibits an I-coefficientor L-coefficient as an index expressing the uniformity thereof whichpreferably falls within the range of 1.0 to 2.5, still preferably 1.0 to2.0. When the I-coefficient or L-coefficient falls within the aboverange, there can be obtained a spun yarn of reduced unevenness and highuniformity. Thus, woven and knit fabrics of high quality can beobtained.

[0046] The uniformity of spun yarn is generally expressed by U% measuredwith the use of Uster unevenness tester. However, the U% is largelyvaried depending on the size (fineness) of spun yarn and the size(fineness) of staple fibers constituting the spun yarn. Therefore, fromthe viewpoint of reducing the effect of the fineness of spun yarn andstaple fibers, it is preferred that the uniformity be expressed by theI-coefficient or L-coefficient which is a ratio to the theoretical limituniformity U_(lim). These coefficients are respectively calculated bythe above formulas (b) and (c), depending on the magnitude of theaverage number of staple fibers constituting the spun yarn, namely, thenumber of constituent staple fibers.

[0047] It is preferred that the twist of the spun yarn of the presentinvention be appropriately set in conformity with the fiber length sothat the twist multiplier α (α=twist (T/m)/(metric count^(0.5))) interms of metric count falls within the range of 60 to 120. Thestretchability of the spun yarn can be increased by setting the twistfor a level as low as possible within the range that the strength of thespun yarn can be satisfactorily attained.

[0048] It is generally preferred that the single-fiber fineness of thespun yarn of the present invention be in the range of 0.1 to 10.0 dtex.When the spun yarn is used for clothing purposes, the single-fiberfineness is still preferably in the range of 1.0 to 6.0 dtex.

[0049] The fiber length of the staple fibers is preferably in the rangeof about 30 to about 160 mm, and can be selected taking into account theusage, the spinning method, the fiber length of blended other material,etc. From the viewpoint of attaining desirable spinnability andobtaining a spun yarn of high quality, it is preferred that the weightpercentage of staple fibers over the limited cut length (content ofsingle fibers having lengths greater than the set fiber length) be 0.5wt % or less.

[0050] The initial stretching resistance of the poly(trimethyleneterephthalate) staple fibers for use in the spun yarn of the presentinvention is preferably in the range of 10 to 30 cN/dtex, stillpreferably 20 to 30 cN/dtex, and further still preferably 20 to 27cN/dtex. In this connection, producing poly(trimethylene terephthalate)staple fibers whose initial stretching resistance is less than 10cN/dtex is difficult.

[0051] With respect to the poly(trimethylene terephthalate) staplefibers for use in the present invention, the cross section of eachsingle fiber may be uniform or the size may vary in the longitudinaldirection thereof. The morphology of the cross section may be circular,triangular, L-shaped, T-shaped, Y-shaped, W-shaped, eight leaves shaped,flat shaped (degree of flatness in a range from about 1.3 to 4,including, for example, W-shape, I-shape, boomerang shape, corrugation,skewered dumpling shape, cocoon shape and rectangular parallelopipedon),polygonal (for example, dog bone shape), multileaf-shaped, hollow orundefinable.

[0052] In the present invention, the poly(trimethylene terephthalate)refers to a polyester comprising trimethylene terephthalate units asmain repeating units, wherein the content of trimethylene terephthalateunits is preferably 50 mol % or more, more preferably 70 mol % or more,further more preferably 80 mol % or more, and optimally 90 mol % ormore. Thus, the poly(trimethylene terephthalate) comprehends apoly(trimethylene terephthalate) containing other acid component and/orglycol component as a third component in a total amount of preferablyabout 50 mol % or less, still preferably 30 mol % or less, further stillpreferably 20 mol % or less, and optimally 10 mol % or less.

[0053] The poly(trimethylene terephthalate) is synthesized bypolycondensation of terephthalic acid or a functional derivative ofterephthalic acid, such as dimethyl terephthalate, and trimethyleneglycol or a functional derivative thereof in the presence of a catalystunder appropriate reaction conditions. In this synthetic process,copolymerization may be carried out by adding, as appropriate, one ortwo or more third components. Also, the poly(trimethylene terephthalate)may be blended with a polyester other than poly(trimethyleneterephthalate), such as poly(ethylene terephthalate), nylon or the like.

[0054] As the third component which can be added, there can bementioned, for example, an aliphatic dicarboxylic acid (e.g., oxalicacid or adipic acid), an alicyclic dicarboxylic acid (e.g.,cyclohexanedicarboxylic acid), an aromatic dicarboxylic acid (e.g.,isophthalic acid or sodium sulfoisophthalate), an aliphatic glycol(e.g., ethylene glycol, 1,2-propylene glycol or tetramethylene glycol),an alicyclic glycol (e.g., cyclohexanedimethanol), an aliphatic glycolcontaining aromatic group (e.g., 1,4-bis(β-hydroxyethoxy)benzene), apolyether glycol (e.g., polyethylene glycol or polypropylene glycol), analiphatic oxycarboxylic acid (e.g., ω-oxycaproic acid), or an aromaticoxycarboxylic acid (e.g., p-oxybenzoic acid). Furthermore, a compoundhaving one, or three or more ester forming functional groups (benzoicacid or the like, or glycerol or the like) can be used as the thirdcomponent as far as the obtained polymer is substantially linear.

[0055] The poly(trimethylene terephthalate) staple fibers may containmodifiers, for example, a delustering agent such as titanium dioxide, astabilizer such as phosphoric acid, an ultraviolet absorber such as ahydroxybenzophenone derivative, a crystallization nucleating agent suchas talc, a lubricant such as aerosil, an antioxidant such as a hinderedphenol derivative, a flame retardant, an antistatic agent, an antistaticadditive, a delustering additive, a pigment, a fluorescent brightener,an infrared absorber and an antifoaming agent.

[0056] In the present invention, the poly(trimethylene terephthalate)staple fibers are not limited to staple fibers of one type ofpoly(trimethylene terephthalate), and may include staple fibers of twoor more types of poly(trimethylene terephthalate) polymers which aredifferent from each other in the degree of polymerization, copolymercomposition, etc. and staple fibers whose at least one component ispoly(trimethylene terephthalate), which staple fibers further containother components. For example, latent crimp polyester staple fibers canbe mentioned as preferable staple fibers.

[0057] The latent crimp polyester staple fibers refer to staple fiberscomposed of at least two types of polyester components (for example,often joined into a side-by-side type or an eccentric sheath core type),which staple fibers develop crimp when subjected to thermal treatment.With respect to the two types of polyester components, the combiningratio (generally often ranging from 70/30 to 30/70 (weight ratio)) and across sectional configuration in joining interface of a single filament(occasionally linear or curved configuration) are not particularlylimited. The single-fiber fineness thereof is preferably in the range of0.5 to 10 dtex, which range is however not limitative.

[0058] The latent crimp polyester staple fibers are satisfactory as longas at least one component thereof is poly(trimethylene terephthalate).

[0059] For example, there can be mentioned those whose at least onecomponent is poly(trimethylene terephthalate) as disclosed in JapanesePatent Laid-Open No. 2001-40537. Specifically, the disclosed staplefibers consist of a conjugate fiber comprising two types of polyesterpolymers joined to each other in side-by-side form or in the form of aneccentric sheath core. In the conjugate fiber of side-by-side type, themelt viscosity ratio of the two types of polyester polymers ispreferably in the range of 1.00 to 2.00. In the conjugate fiber ofeccentric sheath core type, it is preferred that with respect to theratio of alkali weight reduction velocity between sheath polymer andcore polymer, the velocity of the sheath polymer be 3 times or moregreater than that of the core polymer.

[0060] With respect to particular polymer combinations, a combination ofpoly(trimethylene terephthalate) and poly(ethylene terephthalate) and acombination of poly(trimethylene terephthalate) and poly(butyleneterephthalate) are preferred. Fibers having poly(trimethyleneterephthalate) arranged inside the crimp are especially preferred.

[0061] In the present invention, the latent crimp polyester staplefibers may be those wherein at least one of the polyester componentsconstituting the staple fibers is poly(trimethylene terephthalate), forexample, those wherein the first component consists of poly(trimethyleneterephthalate) while the second component consists of a polymer selectedfrom among polyesters, such as poly(trimethylene terephthalate),poly(ethylene terephthalate) and poly(butylene terephthalate), andnylons, the first component and the second component arranged inparallel or eccentric relationship into a conjugate spun fiber ofside-by-side type or eccentric sheath core type. In particular, acombination of poly(trimethylene terephthalate) and copolymerizedpoly(trimethylene terephthalate) and a combination of twopoly(trimethylene terephthalate) polymers having different intrinsicviscosity values are preferred.

[0062] Examples of these latent crimp polyester staple fibers aredisclosed in not only the above Japanese Patent Laid-Open No. 2001-40537but also, for example, Japanese Patent Publication No. 43(1968)-19108,Japanese Patent Laid-Open No. 11(1999)-189923, Japanese Patent Laid-OpenNo. 2000-239927, Japanese Patent Laid-Open No. 2000-256918, JapanesePatent Laid-Open No. 2000-328382 and Japanese Patent Laid-Open No.2001-81640.

[0063] The difference of intrinsic viscosity between two types ofpoly(trimethylene terephthalate) polymers is preferably in the range of0.05 to 0.4 dl/g, still preferably 0.1 to 0.35 dl/g and further stillpreferably 0.15 to 0.35 dl/g. For example, when the intrinsic viscosityof high-viscosity side is selected within the range of 0.7 to 1.3 dl/g,it is preferred that the intrinsic viscosity of low-viscosity side beselected within the range of 0.5 to 1.1 dl/g. In this connection, theintrinsic viscosity of low-viscosity side is preferably 0.8 dl/g orgreater, still preferably in the range of 0.85 to 1.0 dl/g, and furtherstill preferably 0.9 to 1.0 dl/g.

[0064] The average intrinsic viscosity of the above conjugate fiber ispreferably in the range of 0.7 to 1.2 dl/g, still preferably 0.8 to 1.2dl/g, further still preferably 0.85 to 1.15 dl/g, and optimally 0.9 to1.1 dl/g.

[0065] The value of intrinsic viscosity expressed in the presentinvention refers not to the viscosity of employed polymer but to theviscosity of the spun yarn. The reason is that the poly(trimethyleneterephthalate) is likely to suffer thermal decomposition as comparedwith poly(ethylene terephthalate) or the like, so that even if a polymerof high intrinsic viscosity is used, the intrinsic viscosity would belowered by thermal decomposition during the spinning step with theresult that with respect to the obtained conjugate fiber, it would bedifficult to maintain the intrinsic viscosity difference between rawpolymers as it was.

[0066] The poly(trimethylene terephthalate) staple fibers for use in thepresent invention can be obtained by, for example, the followingprocess.

[0067] First, filaments are obtained by, for example, the method whereinpoly(trimethylene terephthalate) having an intrinsic viscosity of 0.4 to1.9, preferably 0.7 to 1.2, is melt spun and taken up at a speed ofabout 1500 m/min to thereby obtain an undrawn filament, the undrawnfilament subjected to drawing at a ratio of about 2 to 3.5; the directdrawing method (spin drawing method) wherein the spinning and drawingsteps are directly connected; or the high-speed spinning method (spintake-up method) wherein the take-up speed is 5000 m/min or higher.

[0068] Obtained filaments are continuously formed into a tow.Alternatively, obtained filaments are temporarily wound up into apackage, and thereafter unwound and formed into a tow. Finishing oil forspinning is applied to the tow, and thermal treatment thereof isperformed according to necessity. The resultant tow is crimped byappropriate crimping operation, and cut into given lengths, therebyobtaining desired staple fibers.

[0069] When filaments temporarily wound into a package are unwound andformed into a tow, it is preferred to apply the finishing oil forspinning after removing a finishing oil for filaments having previouslybeen applied to the filaments. Although drawing can be performed afterformation of melt spun undrawn filament into a tow, from the viewpointof obtaining uniform staple fibers, it is preferred that tow formationbe carried out after drawing.

[0070] Use can also made of partially oriented undrawn filamentsobtained by, in the melt spinning, winding at a take-up speed ofpreferably 2000 m/min or greater, still preferably 2500 to 4000 m/min.In that instance, it is preferred that crimping operation be performedafter drawing at natural draw ratio or a lower ratio.

[0071] Alternatively, without cutting into staple fibers in advance, thetow may be supplied in the spinning process, cut into staple fibers withthe use of a tow stretch breaking machine and formed into a spun yarn.

[0072] Although the poly(trimethylene terephthalate) fiber has such apeculiar problem that the interfibrous frictional force thereof is highas compared with that of poly(ethylene terephthalate) fiber or the like,satisfactory spinning characteristics and formation of a spun yarn ofhigh uniformity can be accomplished by applying an appropriate finishingoil for spinning in an appropriate amount.

[0073] In the present invention, the main purpose of the finishing oilapplied to the poly(trimethylene terephthalate) staple fibers is to notonly impart antistatic property but also lower the interfibrousfrictional force so as to enhance the openability of the tow. Further,the main purpose of the finishing oil on the other hand is to impart anappropriate convergence property to the tow and moreover lower the fibervs. metal frictional force to thereby prevent damaging of fibers in theopening step. The finishing oil preferably consists of an anionicsurfactant often used as an antistatic agent. For example, a finishingoil whose main component is an alkyl phosphate salt whose alkyl grouphas 8 to 18 carbon atoms on the average is preferred. A finishing oilwhose main component is an alkyl phosphate potassium salt whose alkylgroup has 8 to 18 carbon atoms on the average is still preferred. Afinishing oil whose main component is an alkyl phosphate potassium saltwhose alkyl group has 10 to 15 carbon atoms on the average is especiallypreferred.

[0074] The alkyl phosphate salt can be, for example, any of laurylphosphate potassium salt (average number of carbon atoms: 12), cetylphosphate potassium salt (average number of carbon atoms: 16) andstearyl phosphate potassium salt (average number of carbon atoms: 18).However, the alkyl phosphate salt for use in the present invention isnot limited to these. The content of alkyl phosphate salt in finishingoil components is preferably in the range of 50 to 100 wt %, stillpreferably 70 to 90 wt %.

[0075] In order to enhance the smoothness of fiber and to preventdamaging of fibers, the finishing oil may contain an animal or vegetableoil, a mineral oil, a fatty acid ester compound, or a nonionic activatorconsisting of, for example, an oxyethylene or oxypropylene compound of afatty acid ester of aliphatic higher alcohol or polyhydric alcohol asanother finishing oil component in an amount of 50 wt % or less,preferably 10 to 30 wt %.

[0076] The amount of adhering finishing oil for spinning is preferablyin the range of 0.05 to 0.5% omf, still preferably 0.1 to 0.35% omf, andfurther still preferably 0.1 to 0.2% omf.

[0077] When the selection of finishing oil is appropriate and the amountof adhering finishing oil falls within the above range, highspinnability can be attained and a spun yarn of high uniformity can beobtained. When the amount of adhering finishing oil is too much,however, wrap on a cylinder is likely to occur in the carding step.Further, wrap on a top roller (rubber roller) is likely to occur in theroller draft operation of drawing step, roving step, spinning step, etc.On the other hand, when the amount of adhering finishing oil is toosmall, damaging of staple fibers is likely to occur in the opening step.Further, the generation of static electricity is likely to be too highin the above roller draft operation, thereby causing wrap on a bottomroller (metal roller). The influence of finishing oil is especiallyconspicuous in the spinning step, and the above wrap of staple fibers ona top roller or bottom roller would invite an increase of end breakageand would deteriorate the uniformity of yarn.

[0078] When it is intended to crimp the poly(trimethylene terephthalate)fiber, the method of crimping is not particularly limited. However, fromthe viewpoint of productivity and excellence of crimp configuration, thestuffer crimping method using a stuffer box is preferred. For ensuringdesirable openability of staple fibers and desirable passage throughprocess steps in the spinning process, it is preferred that the numberof crimps be in the range of 3 to 30 per 25 mm, especially 5 to 20 per25 mm, while the degree of crimp be in the range of 2 to 30%, especially4 to 25%.

[0079] It is preferred that the number of crimps and the degree of crimpbe increased within the above ranges in accordance with the reduction offiber length. Specifically, when the fiber length is 38 mm (cottonspinning process), it is preferred that the number of crimps and thedegree of crimp be 16±2 per 25 mm and 18±3%, respectively. When thefiber length is 51 mm (synthetic fiber spinning process), it ispreferred that the number of crimps and the degree of crimp be 12±2 per25 mm and 15±3%, respectively. With respect to bias cut fibers of 64 mmor more fiber length (worsted spinning process), it is preferred thatthe number of crimps and the degree of crimp be 8±2 per 25 mm and 12±3%,respectively. In the woolen process (uniform fiber length of 51 mm), itis preferred that the number of crimps and the degree of crimp be 18±2per 25 mm and 20±3%, respectively. When the fiber is processed through acarding machine of a high-speed type, the crimp tends to be elongated,so that it is preferred that the degree of crimp be larger by 2 to 5%than the above ranges.

[0080] When the number of crimps and the degree of crimp fall within theabove ranges, at the carding step, the occurrence of web dangling from aweb collecting calender roller or sliver breakage at a coiler calenderroller can be avoided, and desirable passage through a carding machinecan be ensured. Further, high openability can be attained, so that theoccurrence of nep or slub is low. Still further, high spinnability canbe attained, so that a spun yarn of high uniformity and of satisfactoryI-coefficient or L-coefficient can be obtained.

[0081] The process for producing the spun yarn of the present inventionis not particularly limited, and common spinning processes, such as thecotton spinning process (fiber length: 32 mm, 38 mm or 44 mm), thesynthetic fiber spinning process (fiber length: 51 mm, 64 mm or 76 mm),the worsted spinning process (fiber length: 64 mm or greater, bias cut)and the tow spinning process (tow used), can be employed according tothe fiber length of poly(trimethylene terephthalate) staple fibers.Also, the spinning method is not particularly limited, and, for example,the ring spinning method, the rotor type open-end spinning method, thefriction type open-end spinning method, the air jet spinning method, thehollow spindle spinning method (lap spinning method) or the self twistspinning method can be employed. Among these, the ring spinning methodis preferably employed for obtaining a general-purpose spun yarn makingthe best of the softness of poly(trimethylene terephthalate) fiber. Inthe woolen process, it is preferred to employ a mule spinning frame.

[0082] As far as the object of the present invention is not departedfrom, the spun yarn of the present invention may be formed intocomposite spun yarns with various types of filament yarns, for example,a core spun yarn, a twisted spinning yarn, a lapping yarn and variousfancy yarns. According to necessity, the spun yarn may be subjected todoubling (plying or folding) processing or additional twistingprocessing. Moreover, the spun yarn of the present invention may beformed into a composite yarn with another spun yarn, various filamentyarns, a textured yarn or the like by co-twisting, interlacing or fluidjet texturing thereof.

BEST MODE FOR CARRYING OUT THE INVENTION

[0083] The present invention will be described in greater detail belowwith reference to the following Examples and Comparative Examples, whichhowever in no way limit the scope of the present invention.

[0084] The employed measuring method and evaluating method were asfollows.

[0085] (1) Intrinsic Viscosity

[0086] The intrinsic viscosity [η] (dl/g) is a value determined by thedefinition of the following formula:$\lbrack\eta\rbrack = {\lim\limits_{c\rightarrow 0}{\left( {{\eta \quad r} - 1} \right)/C}}$

[0087] wherein ηr is a quotient of the viscosity at 35° C. of a dilutionof poly(trimethylene terephthalate) yarn or poly(ethylene terephthalate)yarn dissolved in an o-chlorophenol solvent of 98% or higher puritydivided by the viscosity, measured at the same temperature, of the abovesolvent, and is defined as a relative viscosity. C is the concentrationof polymer (g/100 ml).

[0088] When the staple fiber comprises a conjugate fiber composed of twoor more types of polymers having different intrinsic viscosity values,it is difficult to measure the respective intrinsic viscosity values ofpolymers constituting the conjugate fiber. Therefore, the intrinsicviscosity obtained by spinning each individual polymer alone under thesame spinning conditions as those of the conjugate fiber and bymeasuring with respect to the thus obtained individual yarn was definedas the intrinsic viscosity of fiber as a constituent of the conjugatefiber.

[0089] (2) Number of Crimps and Degree of Crimp

[0090] These were measured in accordance with the method of measuring anumber of crimps and the method of measuring a degree of crimp asspecified in JIS-L-1015 (method of testing a chemical fiber staple).

[0091] (3) Process Passability (Spinnability)

[0092] 100 kg of poly(trimethylene terephthalate) staple fibers weresupplied in a spinning process, and the passability through a cardingmachine and the occurrence of end breakage during spinning step wereevaluated.

[0093] With respect to the passability through a carding machine, fiberswere processed through a carding machine (flat carding machine in thecotton spinning and synthetic fiber spinning processes, but a rollercarding machine in the worsted spinning process) at a spinning deliveryspeed of 100 m/min, and the wrap on a cylinder, web dangling from a webcollecting calender, sliver breakage, etc. were evaluated.

[0094] With respect to the end breakage during the spinning step, thenumber of end breakages having occurred during continuous production of100 kg of spun yarn by means of one spinning machine (400 spindles) wascounted, and the number of end breakages per hour per spinning machinewas calculated for evaluation of the end breakage characteristics.

[0095] (4) Feeling, Deformation and Durability

[0096] A circular knit fabric was prepared from obtained spun yarn, cut,and made up into sports wears. A wearing test comprising repeatingone-day wearing followed by customary laundering was performed for anextended period of 20 days by ten monitors. With respect to the feeling,deformation and durability, an organoleptic evaluation based on atactile sense and a judgment based on visual inspection were conducted,thereby enabling a relative evaluation.

EXAMPLE 1

[0097] Poly(trimethylene terephthalate) of [η]=0.72 was spun at aspinning temperature of 265° C. and at a spinning speed of 1200 m/min,thereby obtaining an undrawn filament. This filament was drawn undersuch conditions that the hot roll temperature was 60° C., the hot platetemperature 140° C., the draw ratio 3 and the drawing speed 800 m/min,thereby obtaining a drawn filament of 84 dtex/36 f. The strength,elongation and elastic modulus of the drawn filament were 3.5 cN/dtex,45% and 25.3 cN/dtex, respectively.

[0098] 200 thus obtained drawn filaments were formed into a tow, and thefinishing agent for filaments was removed therefrom in a scouring step.Thereafter, a finishing oil for spinning whose main component was laurylphosphate potassium salt was applied thereto in an amount of 0.1% omf.The resultant tow was subjected to a steaming step wherein thermaltreatment was performed at 110° C. and to a stuffer crimping performedat 95° C. with the use of a stuffer box, and thereafter cut into fibersof 51 mm length with the use of an EC cutter. Thus, poly(trimethyleneterephthalate) staple fibers were obtained. The number of crimps anddegree of crimp of obtained poly(trimethylene terephthalate) staplefibers were 11.9 per 25 mm and 12.3%, respectively.

[0099] The obtained poly(trimethylene terephthalate) staple fibers weresupplied in a spinning process according to the common synthetic fiberspinning system wherein a spun yarn was produced from the staple fibersby means of a ring spinning machine. For the spun yarn, twist settingwas performed with the use of a vacuum setting machine at 80° C. for 15min. With respect to the thus obtained spun yarn, the count in terms ofmetric count was 1/51.5 Nm (194.2 dtex), the twist multiplier α 95.3(twist 684 T/m), the U% 14.7%, and the L-coefficient 1.61 (number ofconstituent fibers: 84.4).

[0100] The obtained spun yarn was reeled into a hank, and a hank dyeingwas performed with the use of a bulky spray type dyeing machine atatmospheric pressure. The dyed spun yarn was formed into a circularplain knit fabric with the use of a 30 inch (76.2 cm) and 18 gaugecircular knitting machine.

[0101] With respect to the spun yarn after dyeing, the tenacity(strength), elongation, initial stretching resistance, elastic recoverypercentage of elongation at 5% elongation and other measurement andevaluation results are collectively listed in Table 1.

EXAMPLE 2

[0102] A spun yarn was produced in the same manner as in Example 1except that blend spinning of 67 wt % of poly(trimethyleneterephthalate) staple fibers employed in Example 1 and 33 wt % of cupra(Bemberg: trade name of Asahi Kasei Corporation) staple fibers (1.4 dtexfineness and 51 mm fiber length) was performed in the drawing step, andthat the twist setting was performed at 60° C. for 15 min.

[0103] Thereafter, dyeing and formation of a circular knit fabric werecarried out in the same manner as in Example 1. With respect to the spunyarn after dyeing, the properties and other measurement and evaluationresults are collectively listed in Table 1.

EXAMPLE 3

[0104] A spun yarn was produced in the same manner as in Example 1except that blend spinning of 33 wt % of poly(trimethyleneterephthalate) staple fibers employed in Example 1 and 67 wt % of woolof quality 70 (average fineness: 4.0 dtex, and cut into 51 mm fiberlength) was performed in the drawing step, and that the twist settingwas performed at 70° C. for 15 min. Thereafter, dyeing and formation ofa circular knit fabric were carried out in the same manner as in Example1.

[0105] With respect to the spun yarn after dyeing, the properties andother measurement and evaluation results are collectively listed inTable 1.

EXAMPLE 4

[0106] Poly(trimethylene terephthalate) staple fibers of 1.7 dtexsingle-fiber fineness and 38 mm fiber length were produced in the samemanner as in Example 1. The number of crimps and degree of crimp ofobtained poly(trimethylene terephthalate) staple fibers were 16.4 per 25mm and 15.8%, respectively.

[0107] Sliver blend spinning of 50 wt % of obtained poly(trimethyleneterephthalate) staple fibers and 50 wt % of combed cotton was carriedout in a drawing step, and a spun yarn was produced by a spinningprocess according to the common cotton spinning system. Thereafter,dyeing and formation of a circular knit fabric were carried out in thesame manner as in Example 1.

[0108] With respect to the spun yarn after dyeing, the properties andother measurement and evaluation results are collectively listed inTable 1.

Comparative Example 1

[0109] A spun yarn was produced in the same manner as in Example 1except that poly(ethylene terephthalate) staple fibers of 2.3 dtexfineness and 51 mm fiber length were employed. Thereafter, dyeing andformation of a circular knit fabric were carried out in the same manneras in Example 1.

[0110] With respect to the spun yarn after dyeing, the properties andother measurement and evaluation results are collectively listed inTable 1.

Comparative Example 2

[0111] A spun yarn was produced in the same manner as in Example 1except that blend spinning of 67 wt % of poly(ethylene terephthalate)staple fibers employed in Comparative Example 1 and 33 wt % of cuprastaple fibers (1.4 dtex fineness and 51 mm fiber length) was performed.In the same manner as in Example 1, except that the twist setting wasperformed at 60° C. for 15 min, dyeing and formation of a circular knitfabric were carried out.

[0112] With respect to the spun yarn after dyeing, the properties andother measurement and evaluation results are collectively listed inTable 1.

[0113] All the spun yarns of Examples 1 to 4 exhibited high elongation,so that the knitting performance thereof was strikingly excellent.Further, the initial stretching resistance was slight while theelongation was high, so that such a property of a fabric, that highelongation was attained with low stress, was obtained. Thus, the fabricsexhibited excellent stretchability. Still further, the elastic recoverypercentage of elongation of the spun yarns was high, so that the knitfabrics thereof were excellent in stretch-back property.

[0114] The knit fabrics of Examples 2, 3 and 4 were those whereinwithout excess surfacing of the feeling of poly(trimethyleneterephthalate) fiber, the feeling of cupra, wool and cotton as the othermaterial in the blend was satisfactorily exhibited.

[0115] Wearing test results showed that with respect to the fabrics ofExamples 1 to 4, the changes of feeling and dimension were extremelyslight, and holing, surface worn-out blemish, pilling, etc. did notoccur, whereby the fabric showed excellent durability.

[0116] In Comparative Example 1, the initial stretching resistance ofthe spun yarn was high while the elastic recovery percentage ofelongation thereof was low, so that the knit fabric thereof exhibitedhard feeling, poor stretchability and poor stretch-back property.

[0117] In Comparative Example 2, the elongation of the spun yarn waslow, so that yarn breakage occurred at the time of knitting, therebyattesting to relatively poor knittability. Further, the initialstretching resistance of the spun yarn was high, while the elongationand elastic recovery percentage of elongation thereof were low, so thatboth the stretchability and stretch-back property of the knit fabricwere poor. Still further, the tenacity and elongation product of thespun yarn was low, so that at the wearing test, surface worn-out blemishand pilling occurred, thereby attesting to poor durability.

EXAMPLE 5 TO 9

[0118] The procedure of Example 1 was repeated except that theconditions of stuffer crimping with the use of a stuffer box werechanged, thereby obtaining poly(trimethylene terephthalate) staplefibers differing in the number of crimps and the degree of crimp. Spunyarns were produced from the obtained poly(trimethylene terephthalate)staple fibers in the same manner as in Example 1. Thereafter, dyeing andformation of a circular knit fabric were carried out in the same manneras in Example 1.

[0119] With respect to the spun yarns after dyeing, the properties andother measurement and evaluation results are collectively listed inTable 2.

[0120] All the spun yarns of Examples 5 to 9 exhibited excellentknittability, and the obtained knit fabrics were excellent instretchability and stretch-back property. In the wearing test thereof,the changes of feeling and dimension were extremely slight, and holing,surface worn-out blemish, pilling, etc. did not occur, thereby attestingto excellent durability.

[0121] Such tendencies that the nep and slub of spun yarn were slightlyincreased, the L-coefficient was also increased, and the uniformity ofspun yarn was lowered in accordance with an increase of the number ofcrimps and degree of crimp were recognized. In particular, in Example 5,both the number of crimps and the degree of crimp were considerablylarge, so that the openability of fibers was slightly unsatisfactory,the occurrence of end breakage in the spinning step was slightly high,and a yarn whose L-coefficient exceeded 2.0 attesting to slightly pooruniformity resulted. In Example 9, both the number of crimps and thedegree of crimp were considerably small, so that the tendency of webdangling at a web collecting calender zone was recognized in the cardingstep.

EXAMPLES 10 to 14

[0122] Bias-cut poly(trimethylene terephthalate) staple fibers of 2.2dtex fineness and 64 to 89 mm fiber length were produced in the samemanner as in Example 1. However, the conditions of stuffer crimping withthe use of a stuffer box were changed, thereby obtainingpoly(trimethylene terephthalate) staple fibers differing in the numberof crimps and the degree of crimp.

[0123] Individual poly(trimethylene terephthalate) staple fibersobtained were supplied in a worsted spinning process. Blend spinning of30 wt % of poly(trimethylene terephthalate) staple fibers and 70 wt % ofwool of quality 70 (average fineness: 4.0 dtex) was performed in amixing gill step, and formation of a spun yarn was carried out by meansof a ring spinning machine.

[0124] Each of the obtained spun yarns was dyed and formed into acircular knit fabric in the same manner as in Example 1 except that thetwist setting was performed at 70° C. for 15 min.

[0125] With respect to the spun yarns after dyeing, the properties andother measurement and evaluation results are collectively listed inTable 3.

[0126] All the spun yarns of Examples 10 to 14 exhibited excellentknittability, and the obtained knit fabrics were not only excellent instretchability and stretch-back property but also found to be thosesatisfactorily making the most of the feeling of wool. In the wearingtest thereof, the changes of feeling and dimension were extremelyslight, and holing, surface worn-out blemish, pilling, etc. did notoccur, thereby attesting to excellent durability.

[0127] However, as experienced in the above Examples 5 to 9, suchtendencies that the nep and slub of spun yarn were slightly increased,the L-coefficient was also increased, and the uniformity of spun yarnwas lowered in accordance with an increase of the number of crimps anddegree of crimp were recognized. In particular, in Example 10, both thenumber of crimps and the degree of crimp were considerably large, sothat the openability of fibers was slightly unsatisfactory, theoccurrence of end breakage in the spinning step was slightly high, and ayarn whose L-coefficient exceeded 2.0 attesting to slightly pooruniformity resulted. In Example 14, both the number of crimps and thedegree of crimp were considerably small, so that the tendency of webdangling at a web collecting calender zone was recognized in the cardingstep.

EXAMPLES 15 to 18

[0128] Poly(trimethylene terephthalate) staple fibers were produced inthe same manner as in Example 1 except that the ratio of adhesion of thefinishing oil for spinning whose main component was lauryl phosphatepotassium salt was changed. The obtained poly(trimethyleneterephthalate) staple fibers were formed into a spun yarn, dyed andformed into a circular knit fabric in the same manner as in Example 1.

[0129] With respect to the spun yarns after dyeing, the properties andother measurement and evaluation results are collectively listed inTable 4.

[0130] All the spun yarns of Examples 15 to 18 exhibited excellentknittability, and the obtained knit fabrics were excellent instretchability and stretch-back property. In the wearing test thereof,the changes of feeling and dimension were extremely slight, and holing,surface worn-out blemish, pilling, etc. did not occur, thereby attestingto excellent durability.

[0131] In Example 16, the ratio of adhesion of finishing oil wasappropriate, so that the passability through carding machine wasexcellent and the occurrence of end breakage in the spinning step wasvery low, thereby attesting to extremely high spinnability. Further, theL-coefficient thereof was small, thereby attesting to excellentuniformity of yarn.

[0132] In Example 15, the amount of adhering finishing oil was slightlysmall, so that the generation of static electricity in the carding stepand the spinning step was slightly high. In the spinning step, theoccurrence of end breakage attributed to the wrap on a bottom roller wasslightly large. Further, the L-coefficient thereof exceeded 2.0,attesting to slightly poor uniformity.

[0133] In Example 17, the amount of adhering finishing oil was slightlyin excess, so that the occurrence of end breakage attributed to the wrapof staple fibers on a top roller was slightly high in the spinning step.However, the uniformity of yarn was tolerable.

[0134] In Example 18, the amount of adhering finishing oil was inexcess, so that not only was the tendency to wrap on a cylinderrecognized in the carding step but also the occurrence of end breakagewas slightly increased in the spinning step. The L-coefficient thereofexceeded 2.0, attesting to rather unsatisfactory uniformity.

EXAMPLE 19

[0135] Poly(trimethylene terephthalate) staple fibers were produced inthe same manner as in Example 1 except that the finishing agent forfilament whose main components were a fatty acid ester and a polyetherof 1,500 molecular weight was not removed and that the finishing oil forspinning was not applied. The ratio of adhesion of finishing agent was0.12% omf.

[0136] The obtained poly(trimethylene terephthalate) staple fibers wereformed into a spun yarn, dyed and formed into a circular knit fabric inthe same manner as in Example 1 .

[0137] With respect to the spun yarns after dyeing, the properties andother measurement and evaluation results are collectively listed inTable 4.

[0138] The obtained spun yarn exhibited satisfactory knittability, andthe obtained knit fabric was excellent in stretchability andstretch-back property. In the wearing test thereof, satisfactory resultswere attained.

[0139] However, the finishing oil was not most appropriate, so that thegeneration of static electricity in the carding step and the spinningstep was slightly high. In particular, the occurrence of end breakage inthe spinning step was slightly high. Further, the L-coefficient thereofexceeded 2.0, attesting to slightly poor uniformity.

EXAMPLE 20

[0140] Two types of poly(trimethylene terephthalate) polymers havingdifferent intrinsic viscosity values used at a ratio of 1:1 wereextruded into an eccentric sheath core form (high viscosity polymerconstituting the core) so as to obtain an undrawn filament at a spinningtemperature of 265° C. and at a spinning speed of 1500 m/min. Thisfilament was drawn and twisted under such conditions that the hot rolltemperature was 55° C., the hot plate temperature 140° C. and thedrawing speed 400 m/min. With respect to the draw ratio, it was so setthat the fineness after drawing was 84 dtex. Thus, a 84 dtex/36 feccentric sheath core type conjugate multifilament was obtained. Withrespect to the obtained conjugate multifilament, the intrinsic viscosity[η] of the high viscosity side was 0.90 while the intrinsic viscosity[η] of the low viscosity side was 0.70.

[0141] Poly(trimethylene terephthalate) staple fibers of 51 mm fiberlength were produced from the obtained conjugate multifilament in thesame manner as in Example 1 except that the stuffer crimping with theuse of a stuffer box was not effected. The number of crimps and degreeof crimp of obtained poly(trimethylene terephthalate) staple fibers were13.2 per 25 mm and 17.5%, respectively.

[0142] The obtained poly(trimethylene terephthalate) staple fibers wereformed into a spun yarn, dyed and formed into a circular knit fabric inthe same manner as in Example 1.

[0143] With respect to the spun yarns after dyeing, the properties andother measurement and evaluation results are collectively listed inTable 4.

[0144] The obtained spun yarn exhibited satisfactory knittability, andthe obtained knit fabric was excellent in stretchability andstretch-back property. In the wearing test thereof, satisfactory resultswere attained. TABLE 1 Example Example Example Example Comp. Comp. 1 2 34 Ex. 1 Ex. 2 Staple fiber Fiber PTT PTT Bem PTT Wool PTT Cotton PET PETBem Content (%) 100 67 33 33 67 50 50 100 67 33 Single fiber size (dtex)2.3 2.3 1.4 2.3 4.0 1.7 2.1 2.3 2.3 1.4 Fiber length (mm) 51 51 51 51 5138 30 51 51 51 Number of crimps (per 25 mm) 11.9 11.9 12.2 11.9 — 16.4 —13.2 13.2 12.2 Degree of crimp (%) 12.3 12.3 15.1 12.3 — 15.8 — 14.514.5 15.1 Spinnability Passability through carding Good Good Good GoodGood Good machine Spinning end breakage 4.2 6.7 7.2 5.3 5.3 6.4(No./frame-hour) Spun yarn Count (Nm) 1/51.5 1/51.7 1/52.5 1/52.3 1/52.41/52.0 Fineness (dtex) 194.2 193.4 190.5 191.2 190.8 192.3 Twistmultiplier 95.3 95.9 100.8 104.7 94.2 95.3 Number of constituent fibers84.4 101.9 59.2 101.8 83.0 101.3 U% (%) 14.7 12.1 17.3 13.3 14.9 12.5 I(L) coefficient 1.61 1.41 1.66 1.55 1.62 1.46 Spun yarn after dyeingTenacity (cN/dtex) 1.52 1.09 0.81 2.03 3.89 1.62 Elongation (%) 43.926.8 27.6 18.6 14.5 8.6 Tenacity and elongation product 66.7 29.2 22.437.8 56.4 13.9 (cn · % /dtex) Initial stretching resistance 6.7 9.6 7.512.4 37.9 36.6 (cN/dtex) Elastic recovery percentage of 91.4 88.1 85.587.3 72.2 68.0 elongation at 5% elongation (%)

[0145] TABLE 2 Example Example Example Example Example 5 6 7 8 9 Staplefiber Fiber PTT PTT PTT PTT PTT Content (%) 100 100 100 100 100 Singlefiber size (dtex) 2.3 2.3 2.3 2.3 2.3 Fiber length (mm) 51 51 51 51 51Number of crimps (per 25 mm) 16.8 14.5 12.3 10.8 9.7 Degree of crimp (%)25.2 15.6 19.7 13.2 11.5 Spinnability Passability through carding GoodGood Good Good Rather poor machine Spinning end breakage 12.8 5.3 6.15.5 4.7 (No./frame · hour) Spun yarn Count (Nm) 1/52.7 1/52.3 1/52.01/51.8 1.52.1 Fineness (dtex) 189.8 191.2 192.3 193.1 191.9 Twistmultiplier 95.2 95.1 95.3 94.9 94.8 Number of constituent fibers 82.583.1 83.6 84.0 83.4 U % (%) I (L) coefficient 2.10 1.97 1.84 1.55 1.70Spun yarn after dyeing Tenacity (cN/dtex) 1.28 1.36 1.32 1.50 1.62Elongation (%) 40.3 42.9 41.8 44.7 43.1 Tenacity and elongation product51.6 58.3 55.2 67.1 69.8 (cN · % /dtex) Initial stretching resistance7.5 7.2 7.6 6.5 6.9 (cN/dtex) Elastic recovery percentage of 88.6 89.592.2 87.0 88.7 elongation at 5% elongation (%)

[0146] TABLE 3 Example Example Example Example Example 10 11 12 13 14+TL,1/6 Staple fiber Fiber PTT Wool PTT Wool PTT Wool PTT Wool PTT WoolContent (%) 30 70 30 70 30 70 30 70 30 70 Single fiber size (dtex) 2.24.0 2.2 4.0 2.2 4.0 2.2 4.0 2.2 4.0 Fiber length (mm) 64-89 — 64-89 —64-89 — 64-89 — 64-89 — Bias Bias Bias Bias Bias Number of crimps (per25 mm) 12.3 — 11.8 — 10.7 — 9.8 — 6.2 — Degree of crimp (%) 20.5 — 15.2— 14.1 — 12.4 — 10.3 — Spinnability Passability through carding GoodGood Good Good Rather poor machine Spinning end breakage 11.3 6.5 5.37.1 7.5 (No./frame · hour) Spun yarn Count (Nm) 1/48.5 1/47.8 1/48.01/48.3 1/47.5 Fineness (dtex) 206.2 209.2 208.3 207.0 210.5 Twistmultiplier 82.2 83.2 82.4 82.0 82.6 Number of constituent fibers 64.265.1 64.9 64.5 65.5 U% (%) 20.3 18.9 17.6 16.3 17.0 I (L) coefficient2.03 1.90 1.77 1.63 1.71 Spun yarn after dyeing Tenacity (cN/dtex) 0.730.75 0.82 0.78 0.76 Elongation (%) 24.7 25.4 24.6 26.7 27.8 Tenacity andelongation product 18.0 19.1 20.2 20.8 21.1 (cN · %/ dtex) Initialstretching resistance 12.9 13.2 12.8 12.7 12.5 (cN · %/ dtex) Elasticrecovery percentage of 80.8 80.3 79.2 78.8 81.2 elongation at 5%elongation (%)

[0147] TABLE 4 Example Example Example Example Example Example 15 16 1718 19 20 Staple fiber Fiber PTT PTT PTT PTT PTT PTT/PTT Content (%) 100100 100 100 100 100 Single fiber size (dtex) 2.3 2.3 2.3 2.3 2.3 2.3Fiber length (mm) 51 51 51 51 51 51 Number of crimps (per 25 mm) 11.911.9 11.9 11.9 11.9 13.2 Degree of crimp (%) 12.3 12.3 12.3 12.3 12.317.5 Amt. of adhering finishing oil (% omf) 0.03 0.15 0.35 0.55 0.120.10 Spinnability Passability through carding machine Rather poor GoodGood Rather poor Rather poor Good Spinning end breakage 23.8 5.3 13.628.9 28.8 8.4 (No./frame-hour) Spun yarn Count (Nm) 1/52.1 1/51.8 1/52.41/51.9 1/52.3 1/52.2 Fineness (dtex) 191.9 193.1 190.8 192.7 191.2 191.6Twist multiplier 95.2 95.3 94.8 94.9 95.1 95.0 Number of constituentfibers 83.5 83.9 83.0 83.8 83.1 83.3 U% (%) 18.6 14.3 16.2 18.8 19.513.7 I (L) coefficient 2.03 1.57 1.77 2.06 2.13 1.50 Spun yarn afterdyeing Tenacity (cN/dtex) 1.38 1.54 1.51 1.40 1.52 1.48 Elongation (%)40.2 42.8 41.5 39.1 41.8 39.5 Tenacity and elongation product 65.9 62.754.7 63.5 58.5 (cN · %/dtex) Initial stretching resistance 7.0 6.6 6.86.9 6.7 6.2 (cN/dtex) Elastic recovery percentage of 91.7 90.6 89.2 92.191.3 90.4 elongation at 5% elongation (%)

[0148] The abbreviations and expression for fibers employed in thetables have the following meanings:

[0149] PTT: poly(trimethylene terephthalate),

[0150] PET: poly(ethylene terephthalate),

[0151] Bem: Bemberg (trade name for cupra fiber produced by Asahi KaseiCorporation), and

[0152] Wool: wool.

[0153] Industrial Applicability

[0154] The spun yarn of the present invention is excellent in knittingand weaving characteristics. The woven and knit fabrics therefrom areexcellent in stretchability and stretch-back property, and furtherexcellent in shape stability and durability when worn for a prolongedperiod of time. The composite spun yarn of poly(trimethyleneterephthalate) staple fibers and other fibers exerts excellent functionswith respect to stretchability, stretch-back property, shape stability,etc., while satisfactorily making the most of the feeling of othermaterial blended.

[0155] The spun yarn of the present invention is useful for jerseycloths such as tights, socks and sportswear, a covering yarn for anelastic yarn, outer woven and knit fabrics, clothing such as underwear,towel, bath mat, interior fabric such as carpet, bedding and the like.

1. A spun yarn comprising poly(trimethylene terephthalate) staple fibersat a content of at least 15% by weight, said spun yarn having an elasticrecovery percentage of elongation at 5% elongation satisfying theformula: elastic recovery percentage of elongation at 5% elongation (%)≧0.1X+70   (a) wherein X represents the content of poly(trimethyleneterephthalate) staple fibers in the spun yarn (% by weight).
 2. The spunyarn according to claim 1, which is a composite spun yarn comprisingpoly(trimethylene terephthalate) staple fibers and other fibers, whereinthe content of poly(trimethylene terephthalate) staple fibers is in therange of 15 to 70% by weight.
 3. The spun yarn according to claim 1 or2, which exhibits an elongation at break of 10% or greater.
 4. The spunyarn according to claim 1, 2 or 3, which exhibits a tenacity andelongation product of 15 cN·%/dtex or greater.
 5. The spun yarnaccording to any of claims 1 to 4, which exhibits an I-coefficient orL-coefficient of 1.0 to 2.5.
 6. The spun yarn according to any of claims1 to 5, to which a finishing oil has been applied, said finishing oilcontaining an alkyl phosphate salt whose alkyl group has 8 to 18 carbonatoms on the average.